This invention relates to cabinets, cases and other enclosures in which electrical and/or electronic apparatus is mounted on racks, trays or other supports housed in the enclosure. The invention is particularly concerned with enclosures of this kind in which circuit boards are accommodated in racks which are housed in the enclosure and which generally comprise a plurality of mutually spaced pairs of opposed guide rails into any pair of which opposed edges of a circuit board can be slid from the front of the rack, as the circuit board is slid fully home one or more than one edge connector mounted on the circuit board at or near its rear edge effecting electrical connection with a connector or connectors directly or indirectly carried by a backplane at the rear of the enclosure.
With a view to facilitating insertion of a circuit board into, and withdrawal of a circuit board from, a pair of opposed guide rails of the rack, it is the general practice to secure to the front edge of the circuit board, i.e. the trailing edge of the board as it is slid into the rails, a substantially rectangular flat plate, hereinafter referred to as the front plate, which serves as a handle. Neighbouring edges of the front plates of adjacent circuit board when slid fully home in their pairs of guide rails will lie close together so that when circuit boards are accommodated in all the pairs of guide rails of the rack, the front plates of the boards together present a substantially flat surface at the front of the enclosure.
When a circuit board has been slid fully home in its pair of guide rails, it is also the general practice to detachably secure the board in position and this is usually effected by means of fixing screws which pass through opposite ends of the front plate of the board and screw into tapped holes in opposed elongate members which extend transversely across the front of the enclosure adjacent the front ends of the pairs of guide rails. Each elongate member is customarily an extrudate of metal or metal alloy and, for reasons of ease of manufacture and cost, generally the tapped holes for reception of the fixing screws of the front plates of the circuit boards are formed in and mutually spaced along the length of a strip of metal or metal alloy which is separately formed with respect to each extrudate and which is removably housed in a pair of opposed grooves in said extrudate.
Where the edge connector or edge connectors at the rear edge of a circuit board effect a multiplicity of pin and socket connections with a connector or connectors of a backplane, a substantial force is necessary both to effect these connections and, when required, to disconnect the edge connector or connectors from the connector or connectors of the backplane and there have been many proposals to provide, near each end of the front edge of a circuit board or of a front plate secured thereto, a lever which is directly or indirectly pivotably secured to the circuit board and which, when pivoted in one direction co-operates with a "push-in" surface on the adjacent elongate member extending transversely across the front of the enclosure to assist in providing the force necessary to effect said multiplicity of pin and socket connections at the rear of the circuit board and, when said connections are made, will not permit withdrawal of the circuit board unless the lever is pivoted in the opposite direction and which, when the lever is pivoted in the opposite direction co-operates with a "push-out" surface on said adjacent elongate member to assist in providing the force necessary to disconnect said edge connector or connectors from the connector or connectors of the backplane.
It is an object of the present invention to provide, for use with a circuit board to be accommodated in a rack housed in an enclosure and to be electrically connected to a backplane at the rear thereof, an improved device for assisting in insertion of a circuit board in, and extraction of a circuit board from, said enclosure, said improved device hereinafter, for convenience, being referred to as "a circuit board injector/ejector device".
According to the invention, the improved circuit board injector/ejector device comprises a body adapted to be secured to a circuit board or to a front plate secured thereto and a lever pivotally mounted on said body, which lever, when pivoted in one direction, has a surface adapted to co-operate with a "push-in" surface on an adjacent elongate member extending transversely across the front of the rack to assist in providing the force necessary to effect a multiplicity of pin and socket connections at the rear of the circuit board to which the device is directly or indirectly secured, and has at least one surface which, when said connections have been made, is adapted to co-operate with a surface on said adjacent elongate member to prevent withdrawal of the circuit board from the rack unless the lever is pivoted in the opposite direction and which lever, when pivoted in said opposite direction, has another surface adapted to co-operate with a "push-out" surface on said adjacent elongate member to assist in providing the force necessary to effect disconnection of said multiplicity of pin and socket connections at the rear of the circuit board, wherein the lever has passing therethrough a fixing screw which, when the multiplicity of pin and socket connections at the rear of the circuit board have been made and withdrawal of the circuit board from the rack is prevented by said co-operating surfaces of the lever and adjacent elongate member, is adapted to screw into a tapped hole in the body of the device or in the front plate of the circuit board to prevent pivotal movement of the lever.
By providing for clamping of the lever of the improved circuit board injector/ejector device when the multiplicity of pin and socket connections at the rear of the circuit board to which the device is directly or indirectly secured have been made, the requirement to secure each end of the front plate of the circuit board to the adjacent transversely extending elongate member by a fixing screw which screws into a tapped hole in a separately formed strip removably accommodated in the adjacent elongate member is avoided. As a consequence, it is unnecessary to provide, in each adjacent elongate member, a separately formed strip having a plurality of tapped holes mutually spaced along its length, thereby representing a substantial savings in cost. Moreover, since such separately formed strips with tapped holes are rendered superfluous by the improved circuit board injector/ejector device of the present invention, the improved device is especially suitable for use in conjunction with the improved elongate member which has mutually spaced along its length guides for reception of locating pins protruding from the rear faces of face plates of circuit boards and which is the subject of co-pending patent application Ser. No: 07/987,804 filed on the same day as the present application.
The invention also includes a circuit board for accommodating in a rack housed in an enclosure and for effecting electrical connection to a backplane at the rear of the enclosure, which circuit board comprises at least one edge connector mounted on the circuit board at or near its rear edge for effecting a multiplicity of pin and socket electrical connections with a connector directly or indirectly carried by a backplane at the rear of the enclosure, a substantially rectangular front plate secured to the front edge of the circuit board and, at or near each end of the front plate, an improved circuit board injector/ejector device as hereinbefore described.